Sum of primes < 2^n.

Terms

a(0) =0a(1) =5a(2) =17a(3) =41a(4) =160a(5) =501a(6) =1720a(7) =6081a(8) =22548a(9) =80189a(10) =289176a(11) =1070091a(12) =3908641a(13) =14584641a(14) =54056763a(15) =202288087a(16) =761593692a(17) =2867816043a(18) =10862883985a(19) =41162256126a(20) =156592635694a(21) =596946687124